Sharpening device



July 29, 1941. H. L. HlNDLE, JR

SHARPENING DEVICE Filed Dec. 18, 1940 INVENTOR EJR.

ATTORNEY HENRY L. HINDL Patented July 29, 1941 UNHTED res ee'rnr 1 Claim.

My invention relates to a new and useful sharpening device and it relates more particularly to a sharpening device especially adapted for sharpening and resharpening safety razor blades whether they be of the single or double edge variety, it being understood that my device is also adapted for the sharpening of other blades or cutting edges.

Razor blades are now manuiactured along mass production methods so that it is safe to say that there are no blades on the market today which can be used for any length of time without resharpening. It is also often true that blades which are altogether new do not have a really sharp edge to permit rapid, comfortable and effective shaving.

I am aware that a number of manual, automatic and semi-automatic devices for sharpening razor blades and the like have been produced, but, as far as I am aware, all these devices heretofore known have been objectionable in one respect or another such as being expensive and cumbersome, or not being eiiective, or both.

It is therefore the object of my invention to produce an extremely inexpensive and, barring breakage, an indefinitely lasting device and one which can be operated without any skill or particular attention. I have used a working specimen of my device and have succeeded in prolonging the life of a single razor blade, which was used every day, for a period of several months.

The primary requirement in sharpening a blade, or, for that matter, any other cutting edge, is to present the more or less bevelled cutting edge at exactly the proper angle to a relatively harder wearing surface with just the right amount of pressure. It therefore takes considerable skill, which only expert barbers possess for instance, to sharpen a straight razor on a Whetstone or a strop and the same would be true except more so in the case of a. razor blade which has no handle by means of which it can be adequately grasped. It is therefore of the essence of my invention that my device is so constructed that, without any skill and practically automatically, the proper relationship between the cutting edge of the blade and the wearing or sharpening surface, as well as the amount of pressure that is to be applied, are predetermined so that not only the operator needs no skill but it is practically impossible for the operator to make an error in carrying out the sharpening operation.

The full nature of construction and advantage of my novel device will be more clearly understood from the following specification and the accompanying drawing in which:

Fig. 1 represents a plan view of a sharpening device embodying my invention. 7

Fig. 2 represents a perspective view of the device shown in Fig. 1.

Fig. 3 represents a section on line 33 of Fig. 1..

Fig. 4 represents a section on line 4-4 of Fig. 3.

Referring to the drawing in which like reference characters indicate like parts, and more particularly to Fig. 2, it Will be seen that my sharpening device comprises an arcuate or curvilinear body portion which may be fully circular or completely cylindrical in form, or which can have an open top so that it is in the form of a truncated circle or cylinder. The body portion is generally designated by the reference numeral 6 and the open portion, in the event that this form of construction is used, is designated by the numeral 8. The outer surface H] of the body portion may be smooth or it may be roughened or knurled to facilitate gripping, the only essential requirement being that the outer contour" should be such as to be easily and firmly grasped by one hand of the operator. The inner surface of the sharpening device is provided with longi-'- tudinal sections [2 which, as will be seen from the drawing, extend the entire length of the device and which, as will be more clearly seen from Figs. 2 and 4, are arcuate or slightly convexed as v ered, of each of the longitudinal, convex sections 12 is about equal to the central half of the entire width of the blade It so that, as shown in full lines in Fig. 4, the central half of the blade I8 registers with and rests upon the longitudinal section which, for the purpose of description, is now designated as IZA, while the marginal portions of the blade [8 rest on the adjacent longitudinal sections which are now referred to as IZB and I20. The blade I8 is shown as slightly convexed in Fig. 4 which is the position it would assume when it is depressed by pressure of the finger of the operator while the blade is being reciprocated in the direction of the arrows in Fig. 4. It will be seen that when the central section of the blade I8 is resting on one of the 1011'! gitudinal sections I2 and is slightly depressed the marginal portions, which are not under pressure of the finger, tend to retain their original straight position thus bringing their bevelled edges 25 and 22 into intimate but yielding contact with the convex surfaces of the adjacent convex sections I2. As the blade I8, for instance, is moved in a left hand direction in Fig. 4, the leading edge 20 thereof gradually disengages from the convex surface of the section IZB, rides freely over the depressed or concave area It and, as the movement continues, the bevelled or tapered edge 26 rides on the convex surface M of the next adjacent convex section which is now designated as I2D. Conversely, when the blade I8 is moved in the opposite direction, the edge 22 becomes the leading edge and that in turn disengages from the convex surface of the section I20, rides over the adjacent depression or concavity I6 and then again comes into engagement with the convex surface I4 of the next adjacent section now designated I2E. The various positions referred to are diagrammatically and approximately illustrated in the two broken line positions of the blade I8 to the right and to the left of Fig. 4. Thus, in the left hand position the edges 29 and 22 are shown out of engagement since they are just clearing the corresponding depressions I5 and, in the position to the right hand side of Fig. 4, the blade I8 is shown at the beginning of its clockwise movement with the edge 20 thereof just coming into engagement with the convex surface of the section IZE and the edge 22 about to ride off the convexed surface of the next adjacent longitudinal section.

Referring again to the full line position of the blade I8 in Fig. 4, it will be seen that the hump or convex surface of the longitudinal section I2A constitutes a limit to the depression of the blade by the finger of the operator so that it cannot be depressed or ooncaved any more than is necessary or absolutely correct to bring the cutting edges 20 and 22 of the blade into proper contact with the concave surfaces of the sections I23 and 12C and on through I2D, IEE, etc. In other words, the convexity of the surface of the sections I2 is such that, when the center of the blade I8 is pressed down by the finger, the angle of incidence of the cutting edges 20 and 22 would in turn be such that the cutting edge itself does not come into contact with anything, and that only the bevelled sides of the cutting edges are in contact and at proper angle with the wearing, convex surface of the longitudinal sections I2. It has been proposed to sharpen razor blades of this character by rubbing them clockwise and counter-clockwise inside of a drinking glass hav-' ing a smooth internalsurface but I found out by experience that a blade can only be sharpened that way by expert manipulation and that even then it is not properly sharpened for the reason that the sharp cutting edge comes in contact with the surface of the glass and is therefore worn down in the same manner and to the same extent as the tapering 0r bevelling immediately preceding the cutting edge. I also found from actual experience that the longitudinal sections I2 having predetermined width, transversely speaking, and having predetermined convexity as viewed in cross section, afford a construction which first permits the deflection of the blade under pressure of the finger to exactly the desired extent and no more, and second that when so deflected the bevelled sides of the cutting edges of the blade are exactly in the right position to come into contact with the juxtaposed slopes or curves of the adjacent sections I2 immediately in the path of movement. The drawing illustrating this invention is not made to scale and it is obvious that alteration in the width as well as the convexity of the longitudinal sections I'2 will have to be made for blades of various thicknesses as well as for blades of various widths and I want it understood that such changes are contemplated as being part and within the scope of the present disclosure.

In the drawing I have illustrated my device as being made of glass which I find presents the necessary smooth and hard surface and which I also find can be molded or die-cast at minimum cost so that the device can be profitably sold for as low as 10 or perhaps less, but I want it understood that my invention is not limited to the use of glass and that any other metallic or non-metallic, natural or artificial material which lends itself to molding or die-casting could be employed without departing from the spirit or scope of this invention.

In order to permit nesting of the sharpening devices one within the other so that a number of them may be packed in a single box, it is merely necessary to increase the opening 8 in the top of the device from the dimensions shown in the drawing to slightly more than a full diameter and this can be done without detracting from the utility or efficiency of the device.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

A razor blade sharpening device comprising an arcuate body portion having an internal diameter substantially in excess of the width of the blade to be sharpened, the inner surface of said body portion being provided with a plurality of substantially identical, longitudinally extending ribs of a convex transverse cross section, the

width of any two of said ribs bein substantially equal to the width of said blade, and the curvature of each of said ribs being such that when the center of said blade is pressed into contact with crest of one of said ribs a cutting edge of said blade is in tangential contact with the crest of an adjacent rib.

HENRY L. HINDLE, JR. 

